Method of treating flourine compound

ABSTRACT

Divalent and trivalent metal salts are added to the solution containing the fluorine compound and the polymer containing fluorine to precipitate the layered double hydroxide containing the fluorine compound between layers. At this time, the polymer containing fluorine suspended in the solution is also coagulated to precipitate. By these processes, the fluorine compound is fixed with high rate to separate from the solution with the polymer containing fluorine, and recovered if necessary. By this treatment process, the fluorine compound and the polymer containing fluorine, contained in the wastewater etc. can be separated easily, and the burden to environment or ecosystem can be reduced.

FIELD OF THE INVENTION

[0001] Present invention relates to a treatment process reducing aburden to environment and ecosystem about a solution containing amolecular anion having a per-fluorocarbon chain as a main component anda polymer containing fluorine. In addition, it is preferable that saidtreatment process recovers the above-mentioned anion to use effectively.Specifically, the present invention relates to a technology, which formsa layered double hydroxide to fix the molecular anion having theper-fluorocarbon chain as a main component and the polymer containingfluorine in the solution, and recovers to reproduce these anionspreferably.

BACKGROUND OF THE INVENTION

[0002] An anion surface-active agent having the per-fluorocarbon chainas a main component is used as an indispensable material of a productionprocess in many fields, such as an emulsion polymerization process ofPTFE (poly-tetra-fluoro-ethylene) and a production process of anelectronic parts industry. Moreover, said anion surface-active agent isalso widely used as a material, which are various paints, a coatingagent, and a fire-extinguishing agent, etc. However, in these productionprocesses, the above-mentioned anion surface-active agent has been usedas a dilute solution, such as several % to 0.01% by weight. Especially,for example, in the emulsion polymerization of PTFE, a lot of fineparticles of PTFE resins to the fluorine anion surface-active agent havesuspended in a solution, so that the efficient fixing and recovering onan industrial scale has been difficult. Moreover, the problem of thisfixing and recovering has not been considered in general because thissolution is dilute. Furthermore, the fluorine compound, such as saidanion surface-active agent, is a hard material to be processed by theactivated sludge processing, which has been widely used as a wastewaterprocessing. However, a harmony of chemical materials to environment orecosystem is required strongly in recent years, and, also about thisfluorine compound, it is started that the necessity of the technologyabout the closing system by fixing, recovering and reproducing isrecognized strongly.

[0003] According to the fixing and recovering of this anionsurface-active agent, the technology using the layered double hydroxidehas been examined to be in practical use about a phosphate anion or anorganic anion, as a scavenger or a removal agent of anions. However,about molecular anion having the per-fluorocarbon chain as a maincomponent, such examinations have not been done previously. In addition,as a conventional technology, it is known that the process, in which anammonium salt of fluoroalkane acid is extracted to recover by using anorganic solvent, such as dichloro-methane or trichloro-methane, wasproposed (Japanese Patent Raid Open No. Shou 61-215346), but thisprocess uses an organic solvent containing chlorine, so that it is notenough for reducing the burden to environment. Moreover, by thisprocess, it is necessary to remove the fine particles of PTFE, which aresuspended in the solution, so that the processing takes time and effortFurthermore, although it is also known that the other process wasproposed, in which fluoroalkane acid was recovered by an ion exchange(WO 99/62858, UK 1314607), it is also necessary to remove the fineparticles of PTFE beforehand in this process.

[0004] In addition, the inventors have already reported the layereddouble hydroxide having anion between layers (Zn₂Al(OH)₆C₇F₁₅CO₂) forthe purpose of a material synthesis (the 76th spring annual meeting ofthe Chemical Society of Japan), about a high concentration aqueoussolution of per-fluoro-octanoic acid ammonium (about 8.6% by weight).However, this report was not for the purpose of fixing and recovering ofthe anion like this invention, about the solution having the wideconcentration range including the dilute solution of 0.1% by weight.Therefore, the process about absorbing or fixing of such fluorinecompound has not been reported yet.

[0005] Disclosure of the Invention

[0006] Present invention provides the treatment technology, about thesolution containing the fluorine compound having the per-fluorocarbonchain and the polymer containing fluorine, in which the layered doublehydroxide having the fluorine compound is formed to precipitate with thepolymer containing fluorine simultaneously. In addition, it ispreferable that said treatment technology fixing to recover efficientlythe anion having the per-fluorocarbon chain as the main component, suchas carboxylic acid ion, sulfonic acid ion, etc., from the aqueoussolution having the wide concentration range including the diluteaqueous solution of 0.1% by weight.

[0007] That is, this invention provides the process comprising thefollowing constitutions.

[0008] [1] A treatment process of a solution containing an organiccompound having a fluorocarbon chain (hereinafter said to as thefluorine compound) and a polymer containing fluorine, the processcomprising,

[0009] adding divalent and trivalent metal salts to said solution,

[0010] forming a layered double hydroxide having the fluorine compoundbetween layers to fix the fluorine compound, and

[0011] precipitating said layered double hydroxide with the polymercontaining fluorine.

[0012] [2] A treatment process of a solution containing the fluorinecompound and a polymer containing fluorine, the process comprising,

[0013] adding divalent and trivalent metal salts to said solution,

[0014] forming a layered double hydroxide having the fluorine compoundbetween layers to fix the fluorine compound,

[0015] precipitating said layered double hydroxide having the fluorinecompound between layers and the polymer containing fluorine,

[0016] recovering a solid part by a solid-liquid separation,

[0017] dissolving said recovered solid part in an acid, and

[0018] separating a fluorine compound or its salt.

[0019] [3] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according to abovementioned process [1 ] or [2], the process further comprising,

[0020] adjusting pH of the solution to more than 4,

[0021] precipitating the layered double hydroxide having the fluorinecompound between layers and the polymer containing fluorine compound.

[0022] [4] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according toabove-mentioned process [1] or [2], the process further comprising,

[0023] adding an alkali to the solution to adjust pH from 4 to 12,

[0024] adding divalent and trivalent metal salts to said solution, and

[0025] precipitating the layered double hydroxide having the fluorinecompound between layers and the polymer containing fluorine.

[0026] [5] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according to any one ofabove- mentioned processes [1] to [4],

[0027] wherein the divalent metal salt is a salt of magnesium, calcium,zinc, nickel, copper, manganese (divalent), or cobalt (divalent), andthe trivalent metal salt is a salt of aluminum, iron, chromium,manganese (trivalent), cobalt (trivalent), potassium, lanthanum, orscandium.

[0028] [6] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according to any one ofabove-mentioned processes [1] to [5],

[0029] wherein the divalent and the trivalent metal salts are chlorides.

[0030] [7] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according to any one ofabove-mentioned processes [1] to [6],

[0031] wherein said fluorine compound is carboxylic acid or sulfonicacid having the fluorocarbon chain, in which the number of carbon ismore than 5.

[0032] [8] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according to any one ofabove- mentioned processes [1] to [7],

[0033] wherein the polymer containing fluorine ispoly-tetra-fluoro-ethylene.

[0034] [9] The treatment process of the solution containing the fluorinecompound and the polymer containing fluorine according to any one ofabove-mentioned processes [1] to [8],

[0035] wherein the layered double hydroxide having the fluorine compoundbetween layers is shown in the following formula [1].

M(II)_(1−X)M(III)_(X)(OH)₂Y_(X/m)·nH₂O  [1]

[0036] where Y is an anion having valence number m of the fluorinecompound having the fluorocarbon chain, M(II) is a divalent metal ion,M(III) is a trivalent metal ion, X is 0.1 to 0.5, and n is 0 or positiveinteger.

[0037] [10] A treatment process for recovering the fluorine compound andits salts, the process comprising,

[0038] precipitating the layered double hydroxide and the polymercontaining fluorine by the treatment process according to any one ofabove mentioned processes [1] to [9],

[0039] recovering the solid part by the solid-liquid separation,

[0040] dissolving said recovered solid part in a mineral acid to recoverthe separated fluorine compound or its salts, or

[0041] heating said mineral acid dissolving the recovered solid part,

[0042] putting quietly to separate an oil layer, and

[0043] taking out an oil layer to recover the fluorine compound and itssalts.

[0044] [11] A treatment process for recovering the fluorine compound andits salts, the process comprising,

[0045] precipitating the layered double hydroxide and the polymercontaining fluorine by the treatment process according to any one ofabove mentioned processes [1] to [9],

[0046] recovering the solid part by the solid-liquid separation,

[0047] contacting said separated solid part with a sodium carbonateaqueous solution,

[0048] recovering the solid part by the solid-liquid separation,

[0049] dispersing the recovered solid part to an organic solvent ,and

[0050] filtering an insoluble solid part from said solvent.

[0051] According to the above-mentioned processes of the presentinvention, the fluorine compound can be fixed stably, to form theprecipitate of the layered double hydroxide (LDH) having the fluorinecompound between layers, by adding divalent and trivalent metal salts tothe solution containing the fluorine compound, such as thesurface-active agent having the per-fluorocarbon chain, and the polymercontaining fluorine. Moreover, since the polymer containing fluorine isprecipitated with said LDH simultaneously, the polymer containingfluorine can be removed from the solution with LDH by the solid-liquidseparation.

[0052] In addition, according to the treatment process of the presentinvention, even when the concentration of the anion aqueous solution ofthe surface-active agent having the per-fluorocarbon chain is less thanseveral % by weight, for example, very low concentration of about 0.01%by weight, this fluorine compound can be fixed with a very high rate ofmore than 90%. Moreover, as the adding metal salt, the safe salt toenvironment can be used, and the recovered layered double hydroxide is asolid, so that it can be processed advantageously in transportation orstorage by drying.

[0053] Hereafter, this invention is explained concretely.

[0054] (A) Formation of the Layered Double Hydroxide

[0055] Present invention is the treatment process, wherein the divalentand trivalent metal salts are added to the aqueous solution containingthe anion of the organic fluorine compound having the fluorocarbon chain(the fluorine compound), such as carboxylic acid ion or sulfonic acidion, etc., and the polymer containing fluorine, such as PTFE, to formLDH containing said anion between the layers. By this process, theabove-mentioned anion is fixed between the layers of LDH, and thepolymer containing fluorine is precipitated simultaneously. In addition,said precipitate is recovered by the solid-liquid separation from thesolution. Specifically, for example, the treatment process of thepresent invention can be applied effectively to the solution, in which afluorine surface-active agent, such as carboxylic acid, is contained asthe fluorine compound having the fluorocarbon chain, andpoly-tetra-fluoro-ethylene is contained as the polymer containingfluorine. Moreover, as said solution containing the fluorine compoundand the polymer containing fluorine, a coagulated wastewater after anemulsion polymerization of poly-tetra-fluoro-ethylene resin can bementioned.

[0056] In the present invention, for example, the layered doublehydroxide having the fluorine compound between the layers is thecompound shown in the following formula [1]. In addition, it isavailable that this compound contains water or not.

M(II)_(1−X)M(III)_(X)(OH)₂Y_(X/m)·nH₂O  [1]

[0057] where Y is the anion having the valence number m of the fluorinecompound having the fluorocarbon chain, M(II) is the divalent metal ion,M(III) is the trivalent metal ion, X is 0.1 to 0.4, and n is 0 orpositive integer.

[0058] The layered double hydroxide of above formula [1] having thefluorine compounds between layers is, for example, the compound that theanion A is replaced by the fluorine compound Y having the fluorocarbonchain, in the compound of the following formula [2].

M(II)_(1−x)M(III)_(x)(OH)₂A_(x/m)·nH₂O  [2]

[0059] where A is the anion having the valence number m, M(II), M(III),X, and n are the same as the formula [1].

[0060] The divalent metal ion is each ion of magnesium, calcium, zinc,nickel, copper, manganese (divalent), or cobalt (divalent). Moreover,the trivalent metal ion is each ion of aluminum, iron, chromium,manganese (trivalent), cobalt (trivalent), gallium, lanthanum, orscandium. A chloride, a sulfate, or a nitrate, etc., can be used as thesources of these ions. In these compounds, since the chloride is easy toreceive and its reaction effect is also good, it is preferably to beused. Moreover, it is also available that these metal salts are themixed compounds having two or more kinds of ion respectively. As theanion having the valence number m, carboxylic acid ion, sulfonic acidion, chlorine ion and nitric acid ion etc. can be used.

[0061] The layered double hydroxide shown in the above-mentioned formula[1] can be formed by adjusting pH to more than 4, preferably 5 to 8, andadding above-mentioned divalent and trivalent metal salts to the aqueoussolution of the fluorine compound having the fluorocarbon chain. Inaddition, it is preferable that the addition of the metal salts is afteror the same time at the adjustment of pH. Specifically, for example, theabove-mentioned layered double hydroxide is precipitated by the way thatthe aqueous solution mixed with the above-mentioned divalent andtrivalent metal salts is dropped gradually in the aqueous solution ofthe fluorine compound having the fluorocarbon chain, until the moleratio becomes to the formula [1], and simultaneously alkali is droppedgradually to adjust pH of the solution to more than 4, preferably 5 to8. Moreover, as alkali, conventional sodium hydroxide, and potassiumhydroxide etc. can be used. In addition, when the divalent metal ion iscalcium or magnesium, it is available that pH of the aqueous solution isin the range of 5 to 12. Regarding the addition of the divalent andtrivalent metal salts, it is preferable that X value of mole ratio is0.1 to 0.5 in the above-mentioned formula [1]. Usually, it takes about 3hours for a natural precipitation of the separated substance at roomtemperature. In addition, it is preferable that the solution is stirred.The formed precipitate can be filtered to recover.

[0062] In the above-mentioned layered double hydroxide, the layereddouble hydroxide having the X value of about 0.33 in the formula [1], isnot only having the large amount of the reception capacity (theabsorption capacity), but also making the stable compound between theabsorbed anion and itself Therefore, said layered double hydroxide isthe most preferable for fixing and recovering the absorbed anion.Moreover, both of the divalent metal ion of zinc or magnesium and thetrivalent metal ion of aluminum or iron, which can form the layereddouble hydroxide, are safe and harmless to environment. In addition,chlorine ion and Na ion used in the forming process of this layereddouble hydroxide are also safe and harmless to environment. Furthermore,by controlling pH of the aqueous solution to near neutral, the influenceto environment by the wastewater can also be removed substantially.

[0063] In addition, as mentioned above, when the precipitate of thelayered double hydroxide having fluorine compound between layers isformed, before or while adjusting pH of the solution and adding themetal salts, it is preferable that the inert gas is bubbled beforehandin the solution containing the fluorine compound and the polymercontaining fluorine to drive out the carbonic acid contained in thesolution. If the carbonic acid is remained in the solution, the metalsalts and the alkali will react with carbonic acid, so that it is notpreferable.

[0064] According to the above-mentioned process for forming the layereddouble hydroxide, the objective anion of the fluorine compound havingthe fluorocarbon chain can be fixed with high efficiency of more than60%, preferably more than 90%. Moreover, according to the treatmentprocess of the present invention, the polymer containing fluorine in thesolution is coagulated to precipitate, with the layered doublehydroxide. From this process, it is supposed that the above-mentionedlayered double hydroxide is reacted as a coagulant.

[0065] In addition, the formed precipitate containing the layered doublehydroxide can be separated by the conventional method of thesolid-liquid separation. As the concrete separation equipment or method,for example, the filtering, a decantation, a centrifugation, athickener, a filter press, a precoat, and a body field, etc. can beused. In addition, it is not limited to these.

[0066] (B) Recovering the Fluorine Compound

[0067] The process for separating the fluorine compound from therecovered layered double hydroxide shown with the formula [1] is thefollowings. The precipitate of this layered double hydroxide isdissolved in the mineral acid having pH of less than 1. At this time,since the fluorine compound is remained in the strong acid withoutdissolving, this remained fluorine compound is recovered by thesolid-liquid separation. On the other hand, when the liquid temperatureof this solution is more than the fusion temperature of the fluorinecompound or its salt, since this fluorine compound is liquefied, thefluorine compound or its salt can be recovered by putting quietly totake out the separated oil layer. Moreover, since the polymer containingfluorine, which is coagulated to precipitate together with the layereddouble hydroxide, is remained in the strong acid without dissolving, thepolymer containing fluorine can be separated as the solid part, bysetting the liquid temperature to more than the fusion temperature ofthe fluorine compound or its salt to liquefy the fluorine compound.

[0068] Specifically, for example, the coagulated precipitate of theprecipitated layered double hydroxide and the polymer containingfluorine, are recovered by the solid-liquid separation, and therecovered substance was dissolved in sulfuric acid etc. having pH ofless than 1. At this time, the divalent and trivalent metal componentsin the layered double hydroxide are dissolved. Moreover, when the liquidtemperature is higher than the fusion temperature of the fluorinecompound or its salt, the fluorine compound or its salt is liquefied. Onthe other hand, since the coagulated substance of the polymer containingfluorine contained in the precipitate, is not dissolved in the strongacid, the coagulated polymer containing fluorine, which is the solidpart, can be separated, by the solid-liquid separation of the solution,while keeping the liquid temperature of more than the fusiontemperature. Therefore, as putting quietly this solution at more thanthe fusion temperature, the water layer containing the divalent andtrivalent metal ions and the oil layer containing the fluorine compoundor its salt can be separated to take out this oil layer. According tosuch separation of liquid and liquid, the polymer containing fluorineand the fluorine compound can be separated easily. The fluorinecompound, such as carboxylic acid, can be recovered with high purity andhigh yield by refining this oil layer by the distillation, etc.

[0069] In addition, when the precipitated layered double hydroxide andthe coagulated precipitate of the polymer containing fluorine, are mixedwith sulfuric acid etc. having pH of less than 1, the temperature of thesolution is raised by heating of dilution generally. From-this reason,when the liquid temperature becomes more than the fusion temperature ofthe fluorine compound or its salt, it is preferable that the filtratecontaining the liquefied fluorine compound and the coagulated polymercontaining fluorine, which is the solid part, can be separated by thesolid-liquid separation to keep the temperature. Moreover, when theliquid temperature is low, it is preferable that said liquid is heated,so that it may become more than the fusion temperature.

[0070] As another process, it is also available that the fluorinecompound and the polymer containing fluorine are separated as the solidpart, by the solid-liquid separation of the solution, where theprecipitate was dissolved in the strong acid, at the liquid temperatureof less than the fusion temperature. Then, the recovered solid part isheated more than the fusion temperature to liquefy the fluorinecompound, so that the coagulated polymer containing fluorine, whichremains as the solid part, is separated from the solution.

[0071] The recovery process using the ion exchange can be used, otherthan the above-mentioned process, where the precipitate is dissolved inthe strong acid. That is, the precipitate containing the layered doublehydroxide etc., which is separated by the solid-liquid separation, isdispersed in the aqueous solution of carbonate, such as sodiumcarbonate. At this time, the divalent and trivalent metal ions, whichhave been fixed in the layered double hydroxide, are ion-exchanged bythe carbonate ion, and to be eluted in the liquid. Then, the solid partis recovered by the solid-liquid separation of said solution anddissolved in an alcohol. The insoluble solid part in the alcohol isfiltered, so that the fluorine compound or its salt can be recovered.

[0072] When the recovered solid part is contacted with the alcohol,although the fluorine compound, such as carboxylic acid, is dissolved inthe alcohol, the coagulated polymer containing fluorine is not dissolvedto remain as the solid part. This alcoholic solution of the fluorinecompound is refined by the distillation, etc., so that the fluorinecompound, such as carboxylic acid, can be recovered with high purity andhigh yield. On the other hand, the coagulated precipitate of the polymercontaining fluorine can be recovered by the conventional method of thesolid-liquid separation. As this separation equipment or method, thefiltering, the decantation, the centrifugation, the thickener, thefilter press, the precoat, the body field, etc. can be used. Inaddition, it is not limited to these.

[0073] (C) Applications

[0074] As mentioned above, according to the treatment process of thepresent invention, the fluorine compound can be fixed by forming thelayered double hydroxide having the fluorine compound between layers,and the polymer containing fluorine suspending in the solution can alsobe coagulated to precipitate with the formation of the precipitation ofthe fluorine compound. Moreover, when the wastewater contains theanions, which are easy to form LDH, such as the carbonate ion and thesulfate ion, as an inter layer substance, the process of the presentinvention can be applied effectively by putting more superfluous amountof the metal salts than the inter layer anions, into the solution.

[0075] Furthermore, according to the treatment process of the presentinvention, the process of the present invention can be developed intothe various methods, such as the ion exchanging method, in which thefluorine compound is absorbed and fixed on the preformed layered doublehydroxide having good ion exchange ability shown in the above-mentionedformula [2], and a re-hydrating method, in which the compound, where thefluorine compound is absorbed and fixed, is baked to reproduce theabsorption ability for reusing, etc.

[0076] The treatment process of the present invention is explainedconcretely with the following examples. In addition, these examples aremeasured under the following conditions. The concentration of thenegative ion in the aqueous solution was measured by the colorimetricmethod using LC/MS analysis or methylene-blue. The calibration curve wasmade by following ways. Five kinds of standard solution, in which 1 to 5ppm by weight of ammonium salt of the above-mentioned negative ions wascontained, were prepared, and 30 ml of said standard solution was takenrespectively to the separatory funnels to be added 10 ml of chloroformand 10 ml of methylene-blue solution. After shaking well, thesesolutions were put quietly for 10 minutes and the calibration carve wasmade by measuring the each absorbance of these solutions using avisible/ultraviolet spectrometer. The measuring wavelength was fixed at635 nm. The absorbance value was in the range of 0 to 1 in thisconcentration range, and the calibration curve showed good linearity.The conditions of the examples and the results are shown in table 1.

EXAMPLE 1 Al—Zn System

[0077] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where the PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 148ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 10 mL of the mixed aqueous solution of aluminum chloride and zincchloride was dropped in 1 L of the wastewater for 3 hours, wherein Al³⁺ion was 0.378 mmol (1.1 times mol of APF0 in the wastewater), and Zn²⁺ion was 0.755 mmol (2.2 times mol of APF0 in the wastewater), in thismixed aqueous solution. In addition, this aqueous solution was stirredby 50 rpm using an anchor aerofoil while dropping. Moreover, whiledropping, the sodium hydroxide aqueous solution of 0.2N was droppedsuitably to adjust pH from more than 6.5 to less than 7.5. Fromimmediately after dropping the mixed aqueous solution of aluminumchloride and zinc chloride, the very thin milk white liquid began tocoagulate to form the white precipitate. The formation of theprecipitate was finished in 3 hours after starting the dropping of thismixed aqueous solution. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was dried at70° C. for 15 hours with the filter paper. The weight of the driedprecipitate was 2.50 g. When the dried precipitate was analyzed by adifferential thermogravimetric analysis (DTA), an infrared absorptionspectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent,i.e., per-fluoro-octanoic acid, and the layered double hydroxide weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 2 ppm. Therefore,the fixing ratio of the per-fluoro-octanoic acid contained in thelayered double hydroxide was 98.6%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene in the supernatant liquor was less than 50ppm, so that the precipitation rate was more than 98%.

EXAMPLE 2 Al—Mg System

[0078] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,wherein PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 200ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 10. The liquid temperature was 26° C. Next,about 10 mL of the mixed aqueous solution of aluminum chloride andmagnesium chloride was dropped in 1 L of this wastewater for 3 hours,wherein Al³⁺ ion was 0.603 mmol (1.3 times mol of APF0 in thewastewater) and Mg²⁺ ion was 1.21 mmol (2.6 times mol of APF0 in thewastewater) in the mixed aqueous solution. In addition, this aqueoussolution was stirred by 100 rpm using the anchor aerofoil whiledropping. Moreover, while dropping, the sodium hydroxide aqueoussolution of 0.2N was dropped suitably to adjust pH from more than 9 toless than 10. From immediately after dropping the mixed aqueous solutionof aluminum chloride and magnesium chloride, the very thin milk whiteliquid began to coagulate to form the white precipitate. The formationof the precipitate was finished in 3 hours after starting the droppingof this mixed aqueous solution. When the stirring was stopped, theformed precipitate fell down rapidly to be completed in about 5 minutes.The supernatant liquor was transparent and colorless. The precipitatewas filtered by the membrane filter of 3 μm. This precipitate was driedat 70° C. for 15 hours with the filter paper. The weight of the driedprecipitate was 2.54 g. When the dried precipitate was analyzed by thedifferential thermogravimetric analysis (DTA), the infrared absorptionspectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 8 ppm. Therefore,the fixing ratio of the per-fluoro-octanoic acid contained in thelayered double hydroxide was 95.9%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of the supernatant liquor was less than 50ppm, and this precipitation rate was more than 98%.

EXAMPLE 3 Al—Mg System, Superfluous Addition

[0079] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,wherein PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 148ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 10 mL of the mixed aqueous solution of aluminum chloride andmagnesium chloride was dropped in 1 L of said wastewater for 3 hours,wherein Al³⁺ ion was 4.46 mmol (13 times mol of APF0 in the wastewater)and Mg²⁺ ion was 8.92 mmol (26 times mol of APF0 in the wastewater) inthe mixed aqueous solution. In addition, this aqueous solution wasstirred by 100 rpm using the anchor aerofoil while dropping. Moreover,while dropping, the sodium hydroxide aqueous solution of 0.2N wasdropped suitably to adjust pH from more than 10 to less than 11. Fromimmediately after dropping the mixed aqueous solution of aluminumchloride and magnesium chloride, the very thin milk white liquid beganto coagulate to form the white precipitate. The formation of theprecipitate was finished in 3 hours after starting the dropping of thismixed aqueous solution. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was dried at70° C. for 15 hours with the filter paper. The- weight of the driedprecipitate was 3.56 g. When the dried precipitate was analyzed by thedifferential thermogravimetric analysis (DTA), the infrared absorptionspectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro-octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 2 ppm. Therefore,the fixing ratio of the per-fluoro-octanoic acid contained in thelayered double hydroxide was 98.6%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene in the supernatant liquor was less than 50ppm, and this precipitation rate was more than 98%.

EXAMPLE 4 Al—Zn System, Recovery with Sulfuric Acid

[0080] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 500ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 100 mL of the mixed aqueous solution of aluminum chloride and zincchloride was dropped in 20 L of said waste water for 3 hours, whereinAl³⁺ ion was 30.2 mmol (1.3 times mol of APF0 in the wastewater) andZn²⁺ ion was 69.6 mmol (3.0 times mol of APF0 in the wastewater) in themixed aqueous solution. In addition, this aqueous solution was stirredby 75 rpm using the anchor aerofoil while dropping. Moreover, whiledropping, the sodium hydroxide aqueous solution of 0.2N was droppedsuitably to adjust pH from more than 6.5 to less than 7.5. Fromimmediately after dropping the mixed aqueous solution of aluminumchloride and zinc chloride, the very thin milk white liquid began tocoagulate to form the white precipitate. The formation of theprecipitate was finished in 3 hours after starting the dropping of thismixed aqueous solution. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was dried at70° C. for 15 hours with the filter paper. The weight of the precipitateafter drying was 65.2 g. When the dried precipitate was analyzed by thedifferential thermogravimetric analysis (DTA), the infrared absorptionspectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 3 ppm. Therefore,the fixing ratio of the per-fluoro-octanoic acid contained in thelayered double hydroxide was 99.4%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of supernatant liquor was less than 50 ppm,and this precipitation rate was more than 98%.

[0081] In addition, 40 g of this dried precipitate was added to 120 g ofdilute sulfuric acid, where the concentration was 10%, and this aqueoussolution was stirred at room temperature for 3 hours. After thisprocess, this solution was heated at 70° C. to filter the insolublesolid part. The weight of the filtered solid part was 27.6 g afterdrying. When this filtered solid part was analyzed by DTA and IR, thepeaks belonging to the poly-tetra-fluoro-ethylene resin were detected.On the other hand, the filtrate was put quietly at 70° C. to separatethe aqueous solution of the upper layer containing Zn ion and Al ion,and the oil layer of the lower layer. Then, the oil layer was taken outto be distilled, and 4.0 g of per-fluoro-octanoic acid was obtained.

EXAMPLE 5 Al—Mg System, Recovery with Sulfuric Acid

[0082] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 500ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 1000 mL of the mixed aqueous solution of aluminum chloride andmagnesium chloride was dropped in 20 L of the wastewater for 3 hours,wherein Al³⁺ ion was 46.4 mmol (2.0 times mol of APF0 in the wastewater)and Mg²⁺ ion was 92.8 mmol (4.0 times mol of APF0 in the wastewater) inthe mixed aqueous solution. In addition, this aqueous solution wasstirred by 50 rpm using the anchor aerofoil while dropping. Moreover,while dropping, the sodium hydroxide aqueous solution of 0.2N wasdropped suitably to adjust pH from more than 9 to less than 10. Fromimmediately after dropping the mixed aqueous solution of aluminumchloride and magnesium chloride, the very thin milk white liquid beganto coagulate to form the white precipitate. The formation of theprecipitate was finished after starting the dropping of this mixedaqueous solution in 3 hours. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was drieduntil to the constant weight at 70° C. with the filter paper. The weightof the dried precipitate was 66.6 g. When the dried precipitate wasanalyzed by the differential thermogravimetric analysis (DTA), theinfrared absorption spectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 3 ppm. Therefore,the fixing ratio of the per-fluoro-octanoic acid contained in thelayered double hydroxide was 99.4%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene in the supernatant liquor was less than 50ppm, and this precipitation rate was more than 98%.

[0083] In addition, 40 g of this dried precipitate was added to 120 g ofdilute sulfuric acid, where the concentration was 10%, and this aqueoussolution was stirred at room temperature for 3 hours Then, said solutionwas heated at 70° C. to filter the insoluble solid part. The weight ofthe filtered solid part after drying was 27.0 g. When this filteredsolid part was analyzed by DTA and IR, the peaks belonging to thepoly-tetra-fluoro-ethylene resin were detected. On the other hand, thefiltrate was put quietly at 70° C. to separate the aqueous solutioncontaining Al ion and Mg ion of the upper layer and the oil layer of thelower layer. Then, the oil layer was taken out to be distilled, and 4.0g of per-fluoro-octanoic acid was obtained.

EXAMPLE 6 Al—Zn System, Recovery with Hydrochloric Acid

[0084] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 500ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 100 mL of the mixed aqueous solution of aluminum chloride and zincchloride was dropped in 20 L of said wastewater for 3 hours, whereinAl³⁺ ion was 30.2 mmol (1.3 times mol of APF0 in the wastewater) andZn²⁺ ion was 69.6 mmol (3.0 times mol of APF0 in the wastewater) in themixed aqueous solution. In addition, this aqueous solution was stirredby 75 rpm using the anchor aerofoil while dropping. Moreover, whiledropping, the sodium hydroxide aqueous solution of 0.2N was droppedsuitably to adjust pH from more than 6.5 to less than 7.5. Fromimmediately after dropping of the mixed aqueous solution of aluminumchloride and zinc chloride, the very thin milk white liquid began tocoagulate to form the white precipitate. The formation of theprecipitate was finished in 3 hours after starting the dropping of thismixed aqueous solution. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was dried at70° C. for 15 hours with the filter paper. The weight of the driedprecipitate was 65.0 g. When the dried precipitate was analyzed by thedifferential thermogravimetric analysis (DTA), the infrared absorptionspectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 3 ppm. Therefore,the fixing ratio of the per-fluoro-octanoic acid contained in thelayered double hydroxide was 99.4%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of the supernatant liquor was less than 50ppm, and this precipitation ratio was more than 98%.

[0085] In addition, 40 g of this dried precipitate was added to 120 g ofconcentrated hydrochloric acid, and this aqueous solution was stirred atroom temperature for 3 hours. Then, said solution was heated at 70° C.to filter the insoluble solid part. The weight of the filtered solidpart after drying was 27.8 g. When this filtered solid part was analyzedby DTA and IR, the peaks belonging to the poly-tetra-fluoro-ethyleneresin were detected. On the other hand, the filtrate was put quietly at70° C. to separate the aqueous solution containing Zn ion and Al ion ofthe upper layer, and the oil layer of the lower layer. Then, the oillayer was taken out to be distilled, and 3.9g of per-fluoro-octanoicacid was obtained.

EXAMPLE 7 Al—Mg System, Putting Quietly the Insoluble Solid Part withoutSeparation

[0086] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 500ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 100 mL of the mixed aqueous solution of aluminum chloride andmagnesium chloride was dropped in 20 L of said wastewater for 3 hours,wherein Al³⁺ ion was 46.4 mmol (2.0 times mol of APF0 in the wastewater)and Mg²⁺ ion was 92.8 mmol (4.0 times mol of APF0 in the wastewater) inthe mixed aqueous solution. In addition, this aqueous solution wasstirred by 50 rpm using the anchor aerofoil while dropping. Moreover,while dropping, the sodium hydroxide aqueous solution of 0.2N wasdropped suitably to adjust pH from more than 9 to less than 10. Fromimmediately after dropping the mixed aqueous solution of aluminumchloride and magnesium chloride, the very thin milk white liquid beganto coagulate to form the white precipitate. The formation of theprecipitate was finished after starting the dropping of this mixedaqueous solution in 3 hours. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was drieduntil to the constant weight at 70° C. with the filter paper. The weightof the dried precipitate was 66.6 g. When the dried precipitate wasanalyzed by the differential thermogravimetric analysis (DTA), theinfrared absorption spectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro-octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 3 ppm. Therefore,the fixing ratio of the per-fluoro octanoic acid contained in thelayered double hydroxide was 99.4%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of the supernatant liquor was less than 50ppm, and this precipitation rate was more than 98%.

[0087] In addition, 40 g of this dried precipitate was added to 120 g ofdilute sulfuric acid, where the concentration was 10%, and this aqueoussolution was stirred at room temperature for 3 hours. Then, saidsolution was heated at 70° C. to be put quietly with this liquidtemperature without filtering the insoluble solid part, so that theaqueous solution containing Al ion and Mg ion of the upper layer and theoil layer of the lower layer, were separated. Then, the oil layer wastaken out to be distilled, and 4.1 g of per-fluoro-octanoic acid wasobtained.

EXAMPLE 8 Al—Ca System

[0088] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C₀₀NH₄) was measured to be 1000ppm. In addition, after the pretreatment to remove the influence of thepoly-tetra-fluoro-ethylene resin particles, which were remained in thewastewater, the absorbance was measured. The sodium hydroxide aqueoussolution of 0.2N was added to this wastewater to adjust pH to 7. Theliquid temperature was 26° C. Next, about 10 mL of the mixed aqueoussolution of aluminum chloride and calcium chloride was dropped in 1 L ofsaid wastewater for 3 hours, wherein Al³⁺ion was 2.32 mmol (1.0 time molof APF0 in the wastewater) and Ca²⁺ ion was 4.64 mmol (2.0 times mol ofAPF0 in the wastewater) in the mixed aqueous solution. In addition, thisaqueous solution was stirred by 50 rpm using the anchor aerofoil whiledropping. Moreover, while dropping, the sodium hydroxide aqueoussolution of 0.2N was dropped suitably to adjust pH from more than 9 toless than 10. From immediately after dropping the mixed aqueous solutionof aluminum chloride and calcium chloride, the very thin milk whiteliquid began to coagulate to form the white precipitate. The formationof the precipitate was finished in 3 hours after starting the droppingof this mixed aqueous solution. When the stirring was stopped, theformed precipitate fell down rapidly to be completed in about 5 minutes.The supernatant liquor was transparent and colorless. The precipitatewas filtered by the membrane filter of 3 μm. This precipitate was driedat 70° C. for 15 hours with the filter paper. The weight of the driedprecipitate was 3.22 g. When the dried precipitate was analyzed by thedifferential thermogravimetric analysis (DTA), the infrared absorptionspectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro-octanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-octanoic acid ammonium was 344 ppm.Therefore, the fixing ratio of the per-fluoro-octanoic acid contained inthe layered double hydroxide was 65.6%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of supernatant liquor was less than 50 ppm,and this precipitation rate was more than 98%.

EXAMPLE 9 Al—Mg System/C₉F₁₉C00NH₄

[0089] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-decanoic acid ammonium (C₉F₁₉C00NH₄) was measured to be 500ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 10. The liquid temperature was 26° C. Next,about 100 mL of the mixed aqueous solution of aluminum chloride andmagnesium chloride was dropped in 1 L of said wastewater for 3 hours,wherein Al³⁺ ion was 1.88 mmol (2.0 times mol of APF0 in the wastewater)and Mg²⁺ ion was 3.77 mmol (4.0 times mol of APF0 in the wastewater) inthe mixed aqueous solution. In addition, this aqueous solution wasstirred by 50 rpm using the anchor aerofoil while dropping. Moreover,while dropping, the sodium hydroxide aqueous solution of 0.2N wasdropped suitably to adjust pH from more than 9 to less than 10. Fromimmediately after dropping of the mixed aqueous solution of aluminumchloride and magnesium chloride, the very thin milk white liquid beganto coagulate to form the white precipitate. The formation of theprecipitate was finished in 3 hours after starting the dropping thismixed aqueous solution. When the stirring was stopped, the formedprecipitate fell down rapidly to be completed in about 5 minutes. Thesupernatant liquor was transparent and colorless. The precipitate wasfiltered by the membrane filter of 3 μm. This precipitate was drieduntil to the constant weight at 70° C. with the filter paper. The weightof the dried precipitate was 2.82 g. When the dried precipitate wasanalyzed by the differential thermogravimetric analysis (DTA), theinfrared absorption spectrum (IR), and XRD, the peaks belonging to thepoly-tetra-fluoro-ethylene resin, the negative ion surface-active agent(per-fluoro decanoic acid), and the layered double hydroxide, weredetected. From these results, it was confirmed that the precipitatecomprised the substance that the poly-tetra-fluoro-ethylene resin andthe negative ion surface-active agent were precipitated with the layereddouble hydroxide. When the supernatant liquor was analyzed, theconcentration of per-fluoro-decanoic acid ammonium was 3 ppm. Therefore,the fixing ratio of the per-fluoro-decanoic acid contained in thelayered double hydroxide was 99.4%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of supernatant liquor was less than 50 ppm,and this precipitation rate was more than 98%.

EXAMPLE 10 Al—Zn System/Formation Temperature of LHD was 60° C.

[0090] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 148ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. In addition, this aqueous solution washeated to keep the temperature of 60° C. to 70° C. Next, about 10 mL ofthe mixed aqueous solution of aluminum chloride and zinc chloride wasdropped in 1 L of said wastewater for 3 hours, wherein Al³⁺ ion was0.378 mmol (1.1 times mol of APF0 in the wastewater) and Zn²⁺ ion was0.755 mmol (2.2 times mol of APF0 in the wastewater) in the mixedaqueous solution. In addition, this aqueous solution was stirred by 50rpm using the anchor aerofoil while dropping. Moreover, while dropping,the sodium hydroxide aqueous solution of 0.2N was dropped suitably toadjust pH from more than 6.5 to less than 7.5. From immediately afterdropping the mixed aqueous solution of aluminum chloride and zincchloride, the very thin milk white liquid began to coagulate to form thewhite precipitate. The formation of the precipitate was finished in 3hours after starting the dropping of this mixed aqueous solution. Whenthe stirring was stopped, the formed precipitate fell down rapidly to becompleted in about 5 minutes. The supernatant liquor was transparent andcolorless. The precipitate was filtered by the membrane filter of 3 μm.This precipitate was dried at 70° C. for 15 hours with the filter paper.The weight of the dried precipitate was 2.62 g. When the driedprecipitate was analyzed by the differential thermogravimetric analysis(DTA), the infrared absorption spectrum (IR), and XRD, the peaksbelonging to the poly-tetra-fluoro-ethylene resin, the negative ionsurface-active agent (per-fluoro octanoic acid), and the layered doublehydroxide, were detected. From these results, it was confirmed that theprecipitate comprised the substance that the poly-tetra-fluoro-ethyleneresin and the negative ion surface-active agent were precipitated withthe layered double hydroxide. When the supernatant liquor was analyzed,the concentration of per-fluoro-octanoic acid ammonium was 13 ppm.Therefore, the fixing ratio of the per-fluoro-octanoic acid contained inthe layered double hydroxide was 91.2%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of the supernatant liquor was less than 50ppm, and this precipitation rate was more than 98%.

EXAMPLE 11

[0091] Regarding the coagulated wastewater of thepoly-tetra-fluoro-ethylene resin after the emulsion polymerization,where PTFE concentration was 2300 ppm, the concentration ofper-fluoro-octanoic acid ammonium (C₇F₁₅C00NH₄) was measured to be 500ppm. The sodium hydroxide aqueous solution of 0.2N was added to thiswastewater to adjust pH to 7. The liquid temperature was 26° C. Next,about 10 mL of the mixed aqueous solution of aluminum chloride, zincchloride, and magnesium chloride was dropped in said waste water for 3hours, wherein Al³⁺ ion was 0.232 mmol (1.0 time mol of APF0 in thewastewater), Zn²⁺ ion was 0.232 mmol (1.0 time mol of APF0 in thewastewater), and Mg² ⁺ ion was 0.232 mmol (1.0 time mol of APF0 in thewastewater) in the mixed aqueous solution. Then, the precipitate wasformed by the same processes as the Example 1 excepting to adjust PH ofthe solution from 8 to 9. The weight of the dried precipitate was 2.32g. Moreover, regarding said precipitate, it was confirmed that theprecipitate comprised the substance that the poly-tetra-fluoro-ethyleneresin and the negative ion surface-active agent were precipitated withthe layered double hydroxide, by the same processes as Example 1. Whenthe supernatant liquor was analyzed, the concentration ofper-fluoro-octanoic acid ammonium was 4 ppm. Therefore, the fixing ratioof the per-fluoro-octanoic acid contained in the layered doublehydroxide was 96%. Moreover, the concentration ofpoly-tetra-fluoro-ethylene of the supernatant liquor was less than 50ppm, and this precipitation rate was more than 98%.

[0092] Industrial Applicability

[0093] According to the process of the present invention, the followingsare possible. The fluorine compound, such as the surface-active agenthaving the per-fluorocarbon chain, can be absorbed and fixed stablybetween the layers of the layered double hydroxide, and the polymercontaining fluorine in the solution, such as PTFE, can be coagulated andprecipitated simultaneously. The formation of the layered doublehydroxide and the absorption of the fluorine compound are advancedsimultaneously in the solution, and this layered double hydroxide isformed easily by adding the divalent and trivalent metal salts, so thatthe above-mentioned fluorine compound can be absorbed and fixed easily.Moreover, in the suitable embodiment, when the concentration of theanion aqueous solution of the surface-active agent having theper-fluorocarbon chain is less than several % by weight, for example,very low concentration of about 0.01% by weight, this fluorine compoundcan be fixed at a very high rate of more than 90%. In addition, as theadditional metal salts, the safe salts to environment can be used.Moreover, since the layered double hydroxide can be recovered as asolid, it is advantageously in transportation or storage. Furthermore,according to the treatment process of the present invention, thefluorine compound fixed in the layered double hydroxide can be recoveredefficiently for reuse by the separation. Therefore, the burden toenvironment and ecosystem with the fluorine compound can be reduced, andthe fluorine compound can be reused as the resources. In addition, sincethe polymer containing fluorine in the solution, such as PTFE, can becoagulated and precipitated by fixing of the fluorine compound, thecoagulated wastewater of the polymer containing fluorine can be treatedeffectively, in which such wastewater is drawn off in the productionprocess, such as the emulsion polymerization process of PTFE(poly-tetra-fluoro-ethylene) and the manufacturing process of theelectronic parts industry. TABLE 1 Fixing Concentration FluorineCompound Polymer Additional Precip- Ratio Precip- in in solutionContaining Metal pH itate of itation Supernation Concen- Fluorine Saltsmmol Adjust- Weight Anion Rate of liquor No. Kinds tration in solutionTrivalent Divalent ment (g) % Polymer Anion Polymer 1Per•fluoro•octanoic  148 ppm PTFE Al Zn 6.5 ˜ 7.5 2.50 98.6 98%  2 ppm<50 ppm acid ammonium (C₇F₁₅COONH₄)  1 L 2300 ppm 0.378 (1.1) 0.755(2.2) 2 ″  200 ppm PTFE Al Mg  9 ˜ 10 2.54 95.9 98%  8 ppm <50 ppm  1 L2300 ppm 0.603 (1.3) 1.21 (2.6) 3 ″  148 ppm PTFE Al Mg 10 ˜ 11 3.5698.6 98%  2 ppm <50 ppm  1 L 2300 ppm 4.46 (1.3) 8.92 (2.6) 4 ″  500 ppmPTFE Al Zn 6.5 ˜ 7.5 65.2 99.4 98%  3 ppm <50 ppm  20 L 2300 ppm. 30.2(1.3) 69.6 (3.0) 5 ″  500 ppm PTFE Al Mg  9 ˜ 10 66.6 99.4 98%  3 ppm<50 ppm  20 L 2300 ppm 46.4 (2.0) 92.8 (4.0) 6 Same conditions ofprecipitate formation as No. 4, Recovered precipitate is dissolved inconcentrated hydrochloric acid to recover per•flouro•octanoic acid 7Same conditions of precipitate formation as No. 5, Recovered precipitateis dissolved in dilute sulfuric acid to take out an oil layer ofper•flouo•ocatnoic acid without filtering undissolved 8 ″ 1000 ppm PTFEAl Ca  9 ˜ 10 3.22 65.6 98% 344 ppm <50 ppm  1 L 2300 ppm 2.32 (1.0)4.64 (2.0) 9 Per•fluoro•decanoic  500 ppm PTFE Al Mg  9 ˜ 10 2.82 99.498%  3 ppm <50 ppm acid ammonium (C₉F₁₉COONH₄)  1 L 2300 ppm 1.88 (2.0)3.77 (4.0) 10 Per•fluoro•octanoic  148 ppm PTFE Al Zn 6.5 ˜ 7.5 2.6291.2 98%  13 ppm <50 ppm acid ammonium (Liquid Temperature  1 L 2300 ppm0.378 (1.1) 0.755 (2.2) 50-60° C.) 11 Per•fluoro•octanoic  100 ppm PTFEAl Zn:0.232 8 ˜ 9 2.32 96.0 98%  4 ppm <50 ppm acid ammonium(C₇F₁₅COONH₄)  1 L 2300 ppm 0.232 Mg:0.232

What is claimed is,
 1. a treatment process of a solution containing anorganic compound having a fluorocarbon chain (hereinafter said to as thefluorine compound) and a polymer containing fluorine, the processcomprising, adding divalent and trivalent metal salts to said solution,forming a layered double hydroxide having the fluorine compound betweenlayers to fix the fluorine compound, and precipitating said layereddouble hydroxide with the polymer containing fluorine.
 2. A treatmentprocess of a solution containing the fluorine compound and a polymercontaining fluorine, the process comprising, adding divalent andtrivalent metal salts to said solution, forming a layered doublehydroxide having the fluorine compound between layers to fix thefluorine compound, precipitating said layered double hydroxide havingthe fluorine compound between layers and the polymer containingfluorine, recovering a solid part by a solid-liquid separation,dissolving said recovered solid part in an acid, and separating afluorine compound or its salt.
 3. The treatment process of the solutioncontaining the fluorine compound and the polymer containing fluorineaccording to claim [1] or [2], the process further comprising, adjustingpH of the solution to more than 4, precipitating the layered doublehydroxide having the fluorine compound between layers and the polymercontaining fluorine compound.
 4. The treatment process of the solutioncontaining the fluorine compound and the polymer containing fluorineaccording to claim [1] or [2], the process further comprising, adding analkali to the solution to adjust pH from 4 to 12, adding divalent andtrivalent metal salts to said solution, and precipitating the layereddouble hydroxide having the fluorine compound between layers and thepolymer containing fluorine.
 5. The treatment process of the solutioncontaining the fluorine compound and the polymer containing fluorineaccording to any one of claims [1] to [4], wherein the divalent metalsalt is a salt of magnesium, calcium, zinc, nickel, copper, manganese(divalent), or cobalt (divalent), and the trivalent metal salt is a saltof aluminum, iron, chromium, manganese (trivalent), cobalt (trivalent),potassium, lanthanum, or scandium.
 6. The treatment process of thesolution containing the fluorine compound and the polymer containingfluorine according to any one of claims [1] to [5], wherein the divalentand the trivalent metal salts are chlorides.
 7. The treatment process ofthe solution containing the fluorine compound and the polymer containingfluorine according to any one of claims [1] to [6], wherein saidfluorine compound is carboxylic acid or sulfonic acid having thefluorocarbon chain, in which the number of carbon is more than
 5. 8. Thetreatment process of the solution containing the fluorine compound andthe polymer containing fluorine according to any one of claims [1] to[7], wherein the polymer containing fluorine ispoly-tetra-fluoro-ethylene.
 9. The treatment process of the solutioncontaining the fluorine compound and the polymer containing fluorineaccording to any one of claims [1] to [8], wherein the layered doublehydroxide having the fluorine compound between layers is shown in thefollowing formula [1]. M(II)_(1−X)M(III)_(X)(OH)₂Y_(X/m)·nH₂O  [1] whereY is an anion having valence number m of the fluorine compound havingthe fluorocarbon chain, M(II) is a divalent metal ion, M(III) is atrivalent metal ion, X is 0.1 to 0.5, and n is 0 or positive integer.10. A treatment process for recovering the fluorine compound and itssalts, the process comprising, precipitating the layered doublehydroxide and the polymer containing fluorine by the treatment processaccording to any one of claims [1] to [9], recovering the solid part bythe solid-liquid separation, dissolving said recovered solid part in amineral acid to recover the separated fluorine compound or its salts, orheating said mineral acid dissolving the recovered solid part, puttingquietly to separate an oil layer, and taking out an oil layer to recoverthe fluorine compound and its salts.
 11. A treatment process forrecovering the fluorine compound and its salts, the process comprising,precipitating the layered double hydroxide and the polymer containingfluorine by the treatment process according to any one of claims [1] to[9], recovering the solid art by the solid-liquid separation, contactingsaid separated solid part with a sodium carbonate aqueous solution,recovering the solid part by the solid-liquid separation, dispersing therecovered solid part to an organic solvent ,and filtering an insolublesolid part from said solvent.